IRC bot ident server detection

# OpenVAS Vulnerability Test
# $Id: ident_backdoor.nasl 6063 2017-05-03 09:03:05Z teissa $
# Description: IRC bot ident server detection
#
# Authors:
# Brian Smith-Sweeney ([email protected])
# http://www.smithsweeney.com
#
# Copyright:
# Copyright (C) 2004 Brian Smith-Sweeney
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2,
# as published by the Free Software Foundation
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
#

tag_summary = "This host seems to be running an ident server, but the ident server responds 
to an empty query with a random userid.  This behavior may be indicative of an
irc bot, worm, and/or virus infection. It is very likely this system has 
been compromised.";

tag_solution = "re-install the remote system";

# Created: 9/22/04
# Last Updated: 11/25/04
#
# Revision History:
# v1.1 - first released version
# v1.2
#  * Registered security_message on "port" variable instead of static 113
#  * Made socket timeouts and pause between socket connections variable
#  * Changed default socket timeout to 5 seconds to deal with bots that 
#    refuse connections in quick succession (NOTE: 10 seconds is the most 
#    accurate I've seen, but it makes the test *much* slower)

if(description)
{
	script_id(14841);
	script_version("$Revision: 6063 $");
	script_tag(name:"last_modification", value:"$Date: 2017-05-03 11:03:05 +0200 (Wed, 03 May 2017) $");
	script_tag(name:"creation_date", value:"2005-11-03 14:08:04 +0100 (Thu, 03 Nov 2005)");
 script_tag(name:"cvss_base", value:"10.0");
 script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:C/I:C/A:C");
	name = "IRC bot ident server detection";

	summary = "Determines the presence of a malicious ident server";
	family = "Malware";
	script_name(name);
	script_category(ACT_GATHER_INFO);
  script_tag(name:"qod_type", value:"remote_analysis");
	script_copyright("This script is Copyright (C) 2004 Brian Smith-Sweeney");
	script_family(family);
	script_require_ports("Services/auth", 113);
	script_dependencies("find_service1.nasl");
 script_tag(name : "solution" , value : tag_solution);
 script_tag(name : "summary" , value : tag_summary);
	exit(0);
}

#
# User-defined variables
#
soc_out=3; # Socket connect timeout; increase this for slow ident bots
soc_sleep=5; # Time to wait between socket connections; increase this for bots
             # that don't respond to multiple requests in quick succession
r='\r\n';  # Data to send to the auth server at initial connect

#
# End user-defined variables; you should not have to touch anything below this 
#
include('misc_func.inc');

port = get_kb_item("Services/auth");
if(! port) port = 113;
if (! get_port_state(port)) exit(0);


# Get first response
soc1 = open_sock_tcp(port);
if (! soc1) {
	exit(0);
}
if (send(socket:soc1, data:r)<= 0) exit(0);
r1 = recv_line(socket:soc1,length:1024,timeout:soc_out);
ids1 = split(r1, sep: ':');
if ("USERID" >< ids1[1]) {
	close(soc1);
	sleep(soc_sleep);
	# Get second response
	soc2 = open_sock_tcp(port);
	if (! soc2) {
#Uncomment for debugging	display("oops, can't open the second socket\n");
		exit(0);
	}
	send(socket:soc2, data:r);
	r2 = recv_line(socket:soc2,length:1024,timeout:soc_out);
	ids2 = split(r2, sep: ':');
	close(soc2);
	if ("USERID" >< ids2[1]){
		if (ids1[3]==ids2[3]){
			exit(0);
		}
		security_message(port);
		if (service_is_unknown(port: port)) 
		  register_service(port: port, proto: 'fake-identd');
		set_kb_item(name: 'fake_identd/'+port, value: TRUE);
		exit(0);
	}
}
else close(soc1);